The ribosome plays a key role in cell growth and its regulation. Our goal is to understand how bacteria regulate the production of ribosomes and their growth rate. Bacterial ribosomes contain 3 different RNA and 50-60 different protein molecules. We wish to understand the complex series of events which originate in the transcription of the more than 60 genes for these components and culminate in the formation of the complex, and yet specific, structure of the organelle. More specifically, we wish to identify (as many as possible) genes coding for ribosomal proteins and study their genetic organization and the control of their expression. We have recently shown that many ribosomal protein genes mapped at the str-spc region are transcribed as a single unit. In addition, we have isolated amber mutants which cause a "polar effect" in this region. We shall continue to isolate and characterize such amber mutants. We shall also attempt to prove the presence of the "promotor" for this "transcriptional unit". Finally, we'll attempt to isolate DNA coding for ribosomal proteins and use such DNA to study regulation of the expression of ribosomal protein genes in the DNA-dependent in vitro protein synthesizing system developed recently in our laboratory.